Reservoirs of oil or gas in underground formations are typically covered by an impermeable formation, termed caprock, which prevents the oil or gas from migrating to the surface. When a well borehole is drilled to gain access to a prospective production formation or zone, the original natural seal of the caprock is pierced by the borehole. During construction of a well, the drilled borehole is usually cased, such as with steel tubing.
In abandoning the well, the wellbore must be sealed so as to reestablish the impermeability of the caprock to prevent the vertical migration of fluids through the well from the production zone. In order to seal the wellbore, flow of fluids must be addressed both within the casing and within the annulus between the casing outer wall and wellbore. Sealing of the wellbore may need to meet the Bureau of Safety and Environmental Enforcement regulations and/or address other governmental regulations and environmental concerns. Accordingly, new and better methods and systems for sealing abandoned wells are of continuing interest in the oil and gas industry.